Frequency-Doppler Division Multiplexing Modulation—A Waveform Design for High Doppler Communications

This letter presents a novel multicarrier waveform scheme for high Doppler communications, referred to as frequency-Doppler (FD) division multiplexing (FDDM). The FDDM enables the conversion of the time-varying channel representation in the time-frequency (TF) domain to a static FD domain channel composed of independent Doppler taps. Distinguished from orthogonal frequency division multiplexing (OFDM), FDDM modulates symbols in the FD domain, entailing each symbol to be spread over the entire frame time. Thus, the Doppler diversity can be achieved when a maximum ratio combining (MRC) detector is employed at the receiver. Simulation results show that FDDM outperforms OFDM in high-mobility scenarios. Moreover, the FDDM scheme has been shown to achieve comparable performance to the two-step orthogonal time frequency space (OTFS) approach as well as a better adaptability to the well-established TF domain techniques compared to some low-complexity OTFS implementations.